[root@wangjq examples]# tree
.
├── create-update-delete-deployment
│   ├── main.go
│   └── README.md
├── dynamic-create-update-delete-deployment
│   ├── main.go
│   └── README.md
├── fake-client
│   ├── doc.go
│   ├── main_test.go
│   └── README.md
├── in-cluster-client-configuration
│   ├── Dockerfile
│   ├── main.go
│   └── README.md
├── leader-election
│   ├── main.go
│   └── README.md
├── out-of-cluster-client-configuration
│   ├── main.go
│   └── README.md
├── README.md
└── workqueue
    ├── main.go
    └── README.md

[root@wangjq workqueue]# cat main.go 
/*
Copyright 2017 The Kubernetes Authors.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package main

import (
        "flag"
        "fmt"
        "time"

        "k8s.io/klog"

        v1 "k8s.io/api/core/v1"
        meta_v1 "k8s.io/apimachinery/pkg/apis/meta/v1"
        "k8s.io/apimachinery/pkg/fields"
        "k8s.io/apimachinery/pkg/util/runtime"
        "k8s.io/apimachinery/pkg/util/wait"
        "k8s.io/client-go/kubernetes"
        "k8s.io/client-go/tools/cache"
        "k8s.io/client-go/tools/clientcmd"
        "k8s.io/client-go/util/workqueue"
)

type Controller struct {
        indexer  cache.Indexer
        queue    workqueue.RateLimitingInterface
        informer cache.Controller
}

func NewController(queue workqueue.RateLimitingInterface, indexer cache.Indexer, informer cache.Controller) *Controller {
        return &Controller{
                informer: informer,
                indexer:  indexer,
                queue:    queue,
        }
}

func (c *Controller) processNextItem() bool {
        // Wait until there is a new item in the working queue
        key, quit := c.queue.Get()
        if quit {
                return false
        }
        // Tell the queue that we are done with processing this key. This unblocks the key for other workers
        // This allows safe parallel processing because two pods with the same key are never processed in
        // parallel.
        defer c.queue.Done(key)

        // Invoke the method containing the business logic
        err := c.syncToStdout(key.(string))
        // Handle the error if something went wrong during the execution of the business logic
        c.handleErr(err, key)
        return true
}

// syncToStdout is the business logic of the controller. In this controller it simply prints
// information about the pod to stdout. In case an error happened, it has to simply return the error.
// The retry logic should not be part of the business logic.
func (c *Controller) syncToStdout(key string) error {
        obj, exists, err := c.indexer.GetByKey(key)
        if err != nil {
                klog.Errorf("Fetching object with key %s from store failed with %v", key, err)
                return err
        }

        if !exists {
                // Below we will warm up our cache with a Pod, so that we will see a delete for one pod
                fmt.Printf("Pod %s does not exist anymore\n", key)
        } else {
                // Note that you also have to check the uid if you have a local controlled resource, which
                // is dependent on the actual instance, to detect that a Pod was recreated with the same name
                fmt.Printf("Sync/Add/Update for Pod %s\n", obj.(*v1.Pod).GetName())
        }
        return nil
}

// handleErr checks if an error happened and makes sure we will retry later.
func (c *Controller) handleErr(err error, key interface{}) {
        if err == nil {
                // Forget about the #AddRateLimited history of the key on every successful synchronization.
                // This ensures that future processing of updates for this key is not delayed because of
                // an outdated error history.
                c.queue.Forget(key)
                return
        }

        // This controller retries 5 times if something goes wrong. After that, it stops trying.
        if c.queue.NumRequeues(key) < 5 {
                klog.Infof("Error syncing pod %v: %v", key, err)

                // Re-enqueue the key rate limited. Based on the rate limiter on the
                // queue and the re-enqueue history, the key will be processed later again.
                c.queue.AddRateLimited(key)
                return
        }

        c.queue.Forget(key)
        // Report to an external entity that, even after several retries, we could not successfully process this key
        runtime.HandleError(err)
        klog.Infof("Dropping pod %q out of the queue: %v", key, err)
}

func (c *Controller) Run(threadiness int, stopCh chan struct{}) {
        defer runtime.HandleCrash()

        // Let the workers stop when we are done
        defer c.queue.ShutDown()
        klog.Info("Starting Pod controller")

        go c.informer.Run(stopCh)

        // Wait for all involved caches to be synced, before processing items from the queue is started
        if !cache.WaitForCacheSync(stopCh, c.informer.HasSynced) {
                runtime.HandleError(fmt.Errorf("Timed out waiting for caches to sync"))
                return
        }

        for i := 0; i < threadiness; i++ {
                go wait.Until(c.runWorker, time.Second, stopCh)
        }

        <-stopCh
        klog.Info("Stopping Pod controller")
}

func (c *Controller) runWorker() {
        for c.processNextItem() {
        }
}

func main() {
        var kubeconfig string
        var master string

        flag.StringVar(&kubeconfig, "kubeconfig", "", "absolute path to the kubeconfig file")
        flag.StringVar(&master, "master", "", "master url")
        flag.Parse()

        // creates the connection
        config, err := clientcmd.BuildConfigFromFlags(master, kubeconfig)
        if err != nil {
                klog.Fatal(err)
        }

        // creates the clientset
        clientset, err := kubernetes.NewForConfig(config)
        if err != nil {
                klog.Fatal(err)
        }

        // create the pod watcher
        podListWatcher := cache.NewListWatchFromClient(clientset.CoreV1().RESTClient(), "pods", v1.NamespaceDefault, fields.Everything())

        // create the workqueue
        queue := workqueue.NewRateLimitingQueue(workqueue.DefaultControllerRateLimiter())

        // Bind the workqueue to a cache with the help of an informer. This way we make sure that
        // whenever the cache is updated, the pod key is added to the workqueue.
        // Note that when we finally process the item from the workqueue, we might see a newer version
        // of the Pod than the version which was responsible for triggering the update.
        indexer, informer := cache.NewIndexerInformer(podListWatcher, &v1.Pod{}, 0, cache.ResourceEventHandlerFuncs{
                AddFunc: func(obj interface{}) {
                        key, err := cache.MetaNamespaceKeyFunc(obj)
                        if err == nil {
                                queue.Add(key)
                        }
                },
                UpdateFunc: func(old interface{}, new interface{}) {
                        key, err := cache.MetaNamespaceKeyFunc(new)
                        if err == nil {
                                queue.Add(key)
                        }
                },
                DeleteFunc: func(obj interface{}) {
                        // IndexerInformer uses a delta queue, therefore for deletes we have to use this
                        // key function.
                        key, err := cache.DeletionHandlingMetaNamespaceKeyFunc(obj)
                        if err == nil {
                                queue.Add(key)
                        }
                },
        }, cache.Indexers{})

        controller := NewController(queue, indexer, informer)

        // We can now warm up the cache for initial synchronization.
        // Let's suppose that we knew about a pod "mypod" on our last run, therefore add it to the cache.
        // If this pod is not there anymore, the controller will be notified about the removal after the
        // cache has synchronized.
        indexer.Add(&v1.Pod{
                ObjectMeta: meta_v1.ObjectMeta{
                        Name:      "mypod",
                        Namespace: v1.NamespaceDefault,
                },
        })

        // Now let's start the controller
        stop := make(chan struct{})
        defer close(stop)
        go controller.Run(1, stop)

        // Wait forever
        select {}
}

package main
 
import (
    "flag"
    "k8s.io/client-go/kubernetes"
    "k8s.io/client-go/util/workqueue"
    "k8s.io/sample-controller/pkg/signals"
    "k8s.io/client-go/tools/cache"
    "k8s.io/client-go/tools/clientcmd"
    "github.com/golang/glog"
    "k8s.io/apimachinery/pkg/watch"
    metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
    "k8s.io/apimachinery/pkg/runtime"
    utilruntime "k8s.io/apimachinery/pkg/util/runtime"
    apiv1 "k8s.io/api/core/v1"
    "fmt"
    "k8s.io/apimachinery/pkg/util/wait"
    "time"
)
 
/* 控制器 */
type Controller struct {
    // 此控制器使用的客户端
    clientset kubernetes.Interface
    // 此控制器使用的工作队列
    queue workqueue.RateLimitingInterface
    // 此控制器使用的共享Informer，SharedIndexInformer可以维护缓存中对象的索引
    informer cache.SharedIndexInformer
}
 
/* 主函数 */
var (
    // 参数变量
    masterURL  string
    kubeconfig string
)
// 启动控制器
func (c *Controller) Run(stopCh <-chan struct{}) {
    // 捕获应用程序崩溃并打印日志
    defer utilruntime.HandleCrash()
    // 关闭队列，从而导致Worker结束
    defer c.queue.ShutDown()
 
    glog.Info("启动控制器……")
 
    // 运行Informer
    go c.informer.Run(stopCh)
 
    // 在启动Worker之前，等待缓存同步完成
    if !cache.WaitForCacheSync(stopCh, c.informer.HasSynced) {
        utilruntime.HandleError(fmt.Errorf("同步缓存超时"))
        return
    }
 
    glog.Info("缓存已经同步，准备启动Worker")
    // 循环执行Worker，直到TERM
    wait.Until(c.runWorker, time.Second, stopCh)
}
 
// 启动Worker
func (c *Controller) runWorker() {
    for c.processNextItem() {
    }
}
 
// Worker的逻辑框架
func (c *Controller) processNextItem() bool {
    // 最大重试次数
    maxRetries := 3
 
    // 获取下一个元素，第2个出参提示队列是否已经关闭
    key, quit := c.queue.Get()
    if quit {
        return false
    }
 
    // 总是移除Key
    defer c.queue.Done(key)
 
    // 处理Key
    err := c.processItem(key.(string))
 
    if err == nil {
        // 处理成功，提示队列不再跟踪事件历史
        c.queue.Forget(key)
    } else if c.queue.NumRequeues(key) < maxRetries {
        glog.Errorf("处理%s事件失败，准备重试： %v", key, err)
        c.queue.AddRateLimited(key)
    } else {
        glog.Errorf("处理%s事件失败，放弃： %v", key, err)
        c.queue.Forget(key)
        utilruntime.HandleError(err)
    }
    return true
}
 
// Worker核心逻辑
func (c *Controller) processItem(key string) error {
    glog.Infof("开始处理事件%s", key)
    // 根据Key获取对象
    obj, exists, err := c.informer.GetIndexer().GetByKey(key)
    if err != nil {
        return fmt.Errorf("获取对象%s失败: %v", key, err)
    }
    fmt.Print(obj)
    if !exists {
        // 在这里处理对象删除事件
    } else {
        // 在这里处理对象创建事件
    }
    // 因为不进行Resync，不会有更新事件
    return nil
}
 
func main() {
    // 解析参数，存入上述变量
    flag.Parse()
    cfg, err := clientcmd.BuildConfigFromFlags(masterURL, kubeconfig)
    if err != nil {
        glog.Fatalf("构建kubeconfig失败: %s", err.Error())
    }
    // 创建客户端，Clientset是一系列K8S API的集合
    clientset, err := kubernetes.NewForConfig(cfg)
    if err != nil {
        glog.Fatalf("构建clientset失败: %s", err.Error())
    }
    // 信号处理通道，当进程接收到信号后，此通道可读
    stopCh := signals.SetupSignalHandler()
 
    queue := workqueue.NewRateLimitingQueue(workqueue.DefaultControllerRateLimiter())
 
    informer := cache.NewSharedIndexInformer(
        &cache.ListWatch{
            ListFunc: func(options metav1.ListOptions) (runtime.Object, error) {
                // 仅仅列出所有命名空间的Pod
                return clientset.CoreV1().Pods(metav1.NamespaceAll).List(options)
            },
            WatchFunc: func(options metav1.ListOptions) (watch.Interface, error) {
                return clientset.CoreV1().Pods(metav1.NamespaceAll).Watch(options)
            },
        },
        &apiv1.Pod{},
        0,                // 不进行relist
        cache.Indexers{}, // map[string]IndexFunc
    )
 
    // 添加事件处理回调，仅仅是简单的入队
    informer.AddEventHandler(cache.ResourceEventHandlerFuncs{// 此结构实现ResourceEventHandler
        AddFunc: func(obj interface{}) {
            // 从对象中抽取Key
            key, err := cache.MetaNamespaceKeyFunc(obj)
            if err == nil {
                queue.Add(key)
            }
        },
        DeleteFunc: func(obj interface{}) {
            key, err := cache.DeletionHandlingMetaNamespaceKeyFunc(obj)
            if err == nil {
                queue.Add(key)
            }
        },
    })
 
    // 构建控制器对象
    ctrl := Controller{
        clientset,
        queue,
        informer,
    }
 
    // 启动
    ctrl.Run(stopCh)
}